Apparatus for cutting incrementally changing lengths of material



W. OLSEN 3,400,622 APPARATUS FOR CUTTING INCREMENTALLY CHANGING Sept. 10, 1968 LENGTHS OF MATERIAL Filed March 31, 1966 INVENTOR WILLY OLSEN ATTORNEYS United States Patent 3,400,622 APPARATUS FOR CUTTING INCREMENTALLY CHANGING LENGTHS 0F MATERIAL Willy Olsen, Mount Vernon, Ill., assignor to Olsen Magnetics, Inc., Mount Vernon, 111., a corporation of Illinois Filed Mar. 31, 1966, Ser. No. 539,161 Claims. (Cl. 83-210) ABSTRACT OF THE DISCLOSURE The apparatus cuts strip material into pieces of increasing length. Strip material is fed up to a stop and, upon arrival of the material at the stop, feed is terminated, a shear cuts the material and the cut strip is removed from the machine. Removal of the strip indicates feed and moves the head one increment of length relative to the shear. After a predetermined number of shear operations, the head is moved an abnormally large increment relative to the shear and the cycle then reverses itself and returns the machine to its starting condition.

The present invention relates to strip cutting apparatus for cutting various lengths of magnetic strip to be employed in laminated magnetic cores for inductive devices, especially transformers, and more particularly, to an apparatus capable of cutting various lengths of magnetic strip for use in fabricating a magnetic core of the type disclosed in my copending US. patent application Ser No. 443,929, filed Mar. 30, 1965.

In a standard form of transformer construction, a coil structure is provided with a coil window having a magnetic core passing therethrough and enclosing at least one leg of the coil. The core in this type of structure is normally assembled from a plurality of laminations to provide a generally rectangular or square core configuration. In discussing such a core, the term legs refers to the core member or members passing through the window in the coil and the member or members parallel thereto. The term yokes refers to the members joining the legs. The invention is concerned with the cores for use in inductive apparatus made by assembling the laminations of magnetic strip material in ring shape nested one within the other with each lamination lying in a plane surrounding the axis of the window, shaping the assembly by pressing and then heat treating it to relieve stresses. After heat treatment, the laminations can be separated into groups and each group opened at a joint for reassembly with a leg of the core passing through the coil window.

In accordance with prior art techniques of assembly of such cores, a strip of magnetic material is cut into lengths, such that all of the lengths cut differ in length from each other, to the extent that, when the lengths are each formed into a closed ring with the ends of the lengths abutting, the rings can be fitted one within the other to form a core. The manufacture of the core is completed by the known step of pressing the whole assembly to a required shape and heat treating the assembly to relieve strain and set the core.

In one novel pattern of joints contemplated by my aforesaid application, at least one lamination in each group of laminations is overlapped; the overlapped joints, owing to the overall arrangement of the laminations, being staggered relative to all other overlapped joints. Thus, the usual objection to overlapped joints, that the width of the core is greatly increased, is obviated. On the other hand, a continuous magnetic path about the core is provided for each group of laminations.

It is an object of the present invention to provide ap- 3,490,622 Patented Sept. 10, 1968 paratus for cutting magnetic core laminations suitable for fabrication of cores as described in my aforesaid patent application.

It is another object of the present invention to provide a mechanism for automatically cutting varying lengths of magnetic strip to provide laminations for magnetic cores some of which provide butt joints and some of which provide overlapping joints in the final core assembly.

The above and still further objects, features and advantages of the present invention will become apparent upon consideration of the following detailed description of one specific embodiment thereof, especially when taken in conjunction with the accompanying drawings, wherein:

FIGURE 1 is a diagrammatical representation of the apparatus used for advancing a strip of magnetic material and cutting it into lamination lengths; and

FIGURE 2 is a circuit diagram of an additional feature of the invention.

Referring to FIGURE 1, a strip 1 of oriented magnetic material is advanced from a supply reel 2 by a driving roller 3 rotated by a drive motor 4. The strip reel 2 is itself rotated by a strip feed motor 5, the speed of rotation of which is controlled by a motor control circuit 6, the sensing element for which is a feeler device 6a. The control circuit 6 controls the speed of the motor such as to maintain a stable catenary 7 of the strip 1 between the supply reel 2 and the drive roller 3. The control circuit 6 is completely conventional and forms no part of the present invention.

The strip 1 is advanced longitudinally by the drive roller, through an electromagnetic shear device 8 and through guide means comprising rollers 30 and fiat beds 30 and 31 appropriate to maintain the strip 1 straight and level, until the leading end 9 of the strip 1 makes contact with a sensing switch 10 mounted on an adjustable stop 11. Closure of the switch 10 by the end 9 energizes a cutout relay 12 to open contacts 32 in the supply to the motor and de-energize the motor. Thus, when the leading end 9 of the strip bears against the stop 11, the drive to the strip 1 ceases. The closure of the switch 9 also initiates downward movement of a blade 13 of the shear 8 so that, after the strip 1 is stationary with its leading end 9 in contact with the stop 11, a predetermined length of the strip is cut from the strip supply. After the appropriate time which is determined by an RC timing network 33, the signal generated by the closing of switch 10 actuates a solenoid 34. The solenoid pulls down on the guide 31. The cut length of strip is released from between the guide 31 and rollers 30 and allowed to fall away on to a suitable receptacle (not shown).

As a consequence, the switch 10 opens and the drive by which the strip is advanced is reinstated, i.e., con tacts 32 are closed, the motor 4 is energized and the operation so far described repeated, but with the following modification. After a suitable time interval, the initial closure of the switch 10 by the end 9 of the strip, starts an indexing motor 14 to rotate an indexing screw 15 which indirectly governs the position of the stop 11. In a manner that will hereinafter be explained, the indexing motor rotates in an appropriate direction to retract the stop 11, that is to say, it moves it in a direction away from the shear blade 13.

Specifically, the indexing motor 14 is energized through contacts 37 of a relay 38. The motor 14 also drives, through a belt 15 and a variable speed drive 16, a cam 17 having a notch 18 found in the surface thereof.

An actuating arm 19 of a holding switch 20 carries a cam follower 21 which normally rests in the notch 18 in the cam 17. Immediately upon initiation of rotation of the indexing motor 14 due to closure of switch 10, the arm 19 is raised to close the switch 20 in series with holding contacts 39 and relay 38. Thus, the power supply to the motor 14 is maintained until the cam 17 has completed one revolution and the cam follower 21 again falls into the notch 18. The gear ratio of the variable speed device 16 which is provided with a fine adjustment device 23, is such that the stop 11 takes up a new position appropriate to the production of a further length of the magnetic strip 1 longer than the previously cut length by a calculated increment, which increment is determined by the pitch of the screw 13 and the ratio of the belt drive 15 and the ratio set into the drive 16.

The apparatus shown is appropriate for producing groups of laminae of progressively increasing length in which the increment of length between successive laminations of the groups is equal in all cases and also for producing groups of laminae in which the increment for one or more laminae is greater than for the remainder, to the extent that at least one lamination in the group subsequently forms an overlapping instead of a butting joint. This latter function of the apparatus is controlled by a counter 24, operated by the blade 13 of the shear 8. The counter which can be in the form of a Veeder-Root countor with a crank drive, rotates a cam 28 one rotation for each predetermined number, e.g., ten, down strokes of the shear. On each revolution of the cam 28, a switch 41 is closed and energizes a magnetic sst-ba:k device 25 (solenoid) by which the stop 11 is supported relative to the indexing screw 13. The magnetic set back device 25 retracts the stop 11 (moves it toward the left in FIGURE 1) through a distance supplementing that by which it is retracted by the indexing screw 13.

The arrangement is such that this extra retraction of the stop 11 is maintained only until the next lamination has been cut since cutting the extra length strip operates counter 24, opens the switch 41 and de-energizes the solenoid 25 and, before the leading end 9 of the strip 1 again reaches the stop 11, the stop 11 returns to its normal position relative to the set-back device 25. In other words, it returns to the position it would have occupied had the last distance of retraction been equal to the preceding distance of retraction.

With little modification, the apparatus can be arranged to cut the longest lamination first and the shortest lamination last, by advancing rather than retracting the stop. In this case, however, the counter is preferably set to make the first lamination of each group longer (by temporarily retracting the stop 11) instead of the last of each group.

If a core having butt laminations only is required, the counter is put out of operation and the apparatus produces a stack of laminations of progressively increasing or decreasing length, the relative increments of adjacent laminations being equal. If it is known that the strip is not of uniform thickness and it is known at least roughly how the thickness changes, with experience it is possible to adjust the ratio of the gear box 16 by hand through the fine adjustment 23, during the operation of the apparatus, to make allowance for this known variation of thickness.

After a complete set of laminations has been cut, an operator may return the stop 11 to its starting position by manual operation of a reversing switch. However, the motor may be automatically controlled by employing limit steps.

Referring to FIGURE 2, leads 42 and 43 to the motor 14 are connected to supply line L and L respectively. The supply leads L and L of FIGURE 2 correspond to leads L and L of FIGURE 1 of the accompanying drawings to insure that, when motor 14 is reversed, all apparatus of FIGURE 1 is de-energized except the motor 1'4. Leads 42 and 43 are connected to leads L and L respectively, through normally open switch contacts 44 and 46. Leads L and L are connected to leads L and L .41, through normally closed contacts 47 and 48. Contacts 44 and 46 (normally open) and 47 and 48 (normally closed) and a set of holding contacts 49 (normally open) are elements of a relay 51.

Relay 51 is connected across leads L and L through a normally open limit switch 52. The switch 52 detects end of travel of the stop 11 to the left as viewed in FIG- URE 1. When contact 52 is closed, signifying that all of the laminae for a core have been cut, relay 51 is energized and a holding circuit for the relay is established through holding contacts 49 and a normally closed limit switch 53, connected in series. It is noted that, when relay 51 is energized, the supply motor 14 is reversed. Relay 51 remains energized until stop 11 contacts limit switch 53 and opens it, breaking the holding circuit on the relay.

A dash pot 54 is connected to relay 12 so that the contacts 32 cannot reclose until the reset cycle of the apparatus of FIGURE 2 is complete. This function can be performed electrically by adding another set of contacts to the relay 51 to switch a delay circuit into parallel with the solenoid 12 only when relay 51 is energized.

While I have described and illustrated one specific embodiment of my invention, it will be clear that variations of the details of construction which are spe'ifically illustrated and described may be resorted to without departing from the true spirit and scope of the invention as defined in the appended claims.

What I claim is:

1. An apparatus for cutting sheet material comprising a movable stop, a cutting device located at least a predetermined distance from said movable stop, means for advancing a strip of sheet material through said cutting device to said movable stop, means for sensing arrival of the sheet material at said movable stop, first and second means responsive to said means for sensing for, respectively, discontinuing advance of the sheet material and for actuating said cutting device to cut a length of material from the sheet of material, and further means responsive to said sensing means for moving said movable stop a predetermined distance relative to said cutting device.

2. The combination according to claim 1 further comprising means for removing the cut length of material from against said stop and means responsive thereto for re-energizing said means for advancing.

3. The combination according to claim 1 further comprising means for manually changing the distance said movable stop is moved by said further means.

4. The combination according to claim 1 further comprising means for establishing an initial position for said movable stop and means responsive to said stop acquiring a predetermined position for returning said movable stop to its initial position.

5. The combination according to claim 1 further comprising means responsive to a specified number of actuations of said cutting device for moving said movable stop a distance greater than said predetermined distance.

6. The combination according to claim 1 wherein said movable stop comprises a stop member, an electromagnet, means for mounting said stop member for movement relative to said electromagnet upon energization thereof, and wherein said means for moving said movable stop constitutes means for moving said electromagnet.

7. The combination according to claim 6 further comprising means responsive to a specified number of actuations of said cutting device for energizing said electromagnet.

8. The combination according to claim 6 wherein said means for moving said movable stop comprises a rotary electric motor, said motor being energized by said means for sensing a holding circuit for maintaining said motor energized after the cut length of material is removed from said means for sensing and means for opening said holding circuit upon said motor having rotated through a predetermined number of degrees.

9. The combination according to claim 2 wherein said means for removing comprises a base member extending under said stop, said base member supporting the strip material and means for moving one end of said base member downwardly away from said stop.

10. The combination according to claim 1 wherein said movable stop comprises a stop member, a motive means, means for mounting said stop member on said motive means for movement relative to said motive means upon actuation of said motive means, and wherein said means for moving said movable stop constitutes means for moving said motive means.

References Cited UNITED STATES PATENTS 2/1945 Sommerville 83393 6/1956 MacKinnon 83-238 X 2/1963 Duenke 83238 X 6/1963 Eldred 83-238 X 6/1964 Mosher 83-210 12/1964 Kolodgy 83-419 X FOREIGN PATENTS 5/1959 France.

WILLIAM S. LAWSON, Primary Examiner. 

